Java 使用JPA和Hibernate创建表(联接表)
我是JPA世界的新手,在这里我被这个问题困住了 我尝试的是使用Java 使用JPA和Hibernate创建表(联接表),java,mysql,database,jpa,Java,Mysql,Database,Jpa,我是JPA世界的新手,在这里我被这个问题困住了 我尝试的是使用 new SchemaExport(config).create(true, true); 它给了我这个错误 Exception in thread "main" org.hibernate.AnnotationException: Use of @OneToMany or @ManyToMany targeting an unmapped class: com.hidvd.entities.Customer.orders[
new SchemaExport(config).create(true, true);
它给了我这个错误
Exception in thread "main" org.hibernate.AnnotationException: Use of @OneToMany or @ManyToMany targeting an unmapped class: com.hidvd.entities.Customer.orders[com.hidvd.entities.Order]
我有四个实体叫做
-顾客
-项目
-命令
-医嘱ID
它们都与一对多和多对一的关系有关
这里有一些代码
@Entity
public class Customer {
@Id
@Column(name = "cust_id")
@GeneratedValue(strategy = GenerationType.AUTO)
private int custid;
@Column(length = 50, nullable = false, unique = true)
private String name;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "customer")
private List<Order> orders = new ArrayList<Order>();
}
@Entity(name = "item")
public class Item implements Serializable{
public Item() {
super();
}
@Id
@Basic(optional = false)
@Column(name = "item_id", unique = true, nullable = false)
private int itemid;
private String title;
@OneToMany(fetch = FetchType.LAZY, mappedBy = "item")
private List<Order> orders = new ArrayList<Order>();
@Entity(name = "order")
@AssociationOverrides({
@AssociationOverride(name = "customer",
joinColumns = @JoinColumn(name = "cust_id")),
@AssociationOverride(name = "item",
joinColumns = @JoinColumn(name = "item_id")) })
public class Order implements Serializable {
private OrderId pk = new OrderId();
private Calendar orderedDate;
@Embeddable
public class OrderId implements Serializable{
@ManyToOne
private Customer customer;
@ManyToOne
private Item item;
@实体
公共类客户{
@身份证
@列(name=“cust\u id”)
@GeneratedValue(策略=GenerationType.AUTO)
私人帐户;
@列(长度=50,可空=false,唯一=true)
私有字符串名称;
@OneToMany(fetch=FetchType.LAZY,mappedBy=“customer”)
私有列表顺序=新的ArrayList();
}
@实体(名称=“项目”)
公共类项实现可序列化{
公共项目(){
超级();
}
@身份证
@基本(可选=假)
@列(name=“item_id”,unique=true,nullable=false)
私有int-itemid;
私有字符串标题;
@OneToMany(fetch=FetchType.LAZY,mappedBy=“item”)
私有列表顺序=新的ArrayList();
@实体(名称=“订单”)
@联想超越({
@AssociationOverride(name=“customer”,
joinColumns=@JoinColumn(name=“cust_id”),
@AssociationOverride(name=“item”,
joinColumns=@JoinColumn(name=“item_id”))})
公共类顺序实现可序列化{
private OrderId pk=new OrderId();
私人日历订购日期;
@可嵌入
公共类OrderId实现可序列化{
@许多酮
私人客户;
@许多酮
私人物品;
如有任何建议,将不胜感激。提前感谢:)
- 这是persistence.xml文件
java:/MySQLDS
您应该添加:
<mapping class="Your_class_name_here"/>
像这样:
<mapping class="Customer"/>
在persistence.xml中
还有,你应该看看
希望这有帮助!下面是一个示例,说明persistence.xml文件的外观:
<persistence-unit name="hidvddb">
<jta-data-source>java:/MySQLDS</jta-data-source>
<class>com.hidvd.entities.Customer</class>
<class>com.hidvd.entities.Item </class>
<class>com.hidvd.entities.Order </class>
<class>com.hidvd.entities.Order </class>
<properties>
<property name="showSql" value="true"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
</properties>
</persistence-unit>
java:/MySQLDS
com.hidvd.entities.Customer
com.hidvd.entities.Item
com.hidvd.entities.Order
com.hidvd.entities.Order
或者如果您不希望在persistence.xml文件中声明所有实体
<persistence-unit name="hidvddb">
<jta-data-source>java:/MySQLDS</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="showSql" value="true"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
</properties>
</persistence-unit>
</persistence>
java:/MySQLDS
假的
你能在这里发布你的persistence.xml文件吗?看来hibernate没有接收你的文件entities@ufasoli谢谢我上传了它。你忘了在persistence.xml文件中列出你的实体。你还可以将xml标记false
添加到persistence.xml类中,以指示hibernate拾取带注释的类,即使它们不是t在你的persistence.xml文件中列出谢谢你可能的答案。也许我忽略了JPA,这太难了哈哈。两人都欢呼。但仍然没有运气。谢谢你可能的答案。我可能会继续使用表生成,因为我很忙。再次,谢谢:)看看教程,看看它们是否对你有帮助。你在使用Spring或CDI或任何o吗DI系统?你们是如何引导你们的JPA环境的?@ufasoli我只是按照教程做的。这让我发疯了。哈哈哈
<persistence-unit name="hidvddb">
<jta-data-source>java:/MySQLDS</jta-data-source>
<exclude-unlisted-classes>false</exclude-unlisted-classes>
<properties>
<property name="showSql" value="true"/>
<property name="hibernate.dialect" value="org.hibernate.dialect.MySQLDialect" />
</properties>
</persistence-unit>
</persistence>